THE LARGE WHITE 
299 
in proximity to the food plant. The larvae of the summer 
broods often pupate upon their food plants, when they are 
then normally green in colour, exactly assimilating to their 
environment. The larval state occupies about thirty days. 
Late Appearance of Larvae. In exceptional circumstances 
the larvae of this butterfly have been found fully grown in 
mid-winter. For instance, on January 4th of one year I 
found three larvae of P. brassicae which had just crawled 
up a timber-built building 
for pupation, two had 
already started spinning 
up. It was a cold day but 
sunny and with four de¬ 
grees of frost at midday 
when the ‘ larvae were 
found. Since the 1st it 
had continued freezing. 
All three larvae pupated, 
one on the 10th, one on 
the nth and the other on 
the 14th, a very slow pro¬ 
cess owing to the cold 
weather. These produced 
imagines in the spring. 
The eggs were deposited, 
without doubt, in the pre¬ 
vious September ; there¬ 
fore the late date of hatch¬ 
ing retarded the growth of 
the larvae during the 
damp and cold of late autumn and winter. Two or three 
other instances of the occurrence of these larvae in January 
have been recorded. 
Pupa. The pupa measures 25^40 mm. in length. It is well 
proportioned and angular on the dorsal surface, and the head 
is beaked. The colouring varies considerably, as it greatly 
depends upon the surrounding colour of the object upon 
which it is attached. The normal ground colour is ivory- 
white, or white delicately tinged with pale greenish-ochreous ; 
the whole surface is speckled, blotched and reticulated with 
The Large White depositing eggs. 
Sketched from life. 
